The present invention relates generally to electrochemical cell devices or modules.
An electrochemical cell is typically formed by positioning an electrolyte between and in contact with a cathode and an anode. In some cases, the electrolyte is an electrolytic membrane. Such a cell may be configured in a fuel cell to generate electricity, or in an electrochemical pumping module to do mechanical work. In the latter case, an electrical voltage is applied across the anode and cathode, and gas is generated by the cell to apply external gas pressure in a pumping action. Electrochemical pumps of this type are used in devices for dispensing liquids or fluids in a controlled manner, for example medications, fragrances, and the like. The external gas pressure produced by the cell in some of these cases is applied to a flexible barrier or membrane to force liquid out of an adjacent liquid chamber at a controlled flow rate.
One such fluid delivery device is described in U.S. Pat. No. 4,902,278 of Maget entitled "Fluid Delivery Micropump". In some other cases, the gas pressure is used to move a syringe plunger and this dispenses a fluid, as described in application Ser. No. 08/924,564 referred to above.
In prior art electrochemical modules, the electrolytic membrane, the electrodes and the current collectors are secured together in a sandwich-like assembly. The components are stacked in a flat, parallel arrangement and axially compressed by means of a bolted end plate. In prior art fluid delivery devices (U.S. Pat. No. 4,902,278), the stacked assembly also includes a battery in direct contact with the air cathode. In this instance, an external electrical connection is required to connect the battery to the other electrode on the other side of the electrolytic membrane or ionomer, i.e. the side producing the gas pressure. The requirement for an external lead is a problem in mounting and sealing the electrochemical cell module in a suitable fluid delivery device housing. The external lead also produces problems when scaling up of the small electrochemical cell module to large devices, and in volume manufacture of the modules.